Message 25114 in TECH.WW
From: G8MNY
Date: Fri, 03 Jul 26 06:52:00 Z
Newsgroups: TECH.WW
Subject: Spectrum IF Demo circuit
Message-ID: <64022_GB7CIP>
Path: N2NOV|N2MH|VE2PKT|VK3AT|VK7AX|GB7CIP
R:260703/0655z @:N2NOV.#RICH.NY.USA.NOAM $:64022_GB7CIP
R:260703/0655z @:N2MH.#NNJ.NJ.USA.NOAM [via AREDN Mesh] jnos 2.0p $:64022_GB7CIP
R:260703/0655Z 12257@VE2PKT.#TRV.QC.CAN.NOAM LinBPQ6.0.25
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R:260703/0652Z @:GB7CIP.#32.GBR.EURO #:64022 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (New Feb 10)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
Being involved with course ham training with practicals, I have been doing all
the technical demos for the advanced course, this one shows "under", "critical"
and "over" coupling between 2 tuned circuits.
SETUP
I cheated with the use of my RF Noise Bridge as a noise source and my Crystal
Set with its 2 sliding coils on a ferrite rod, as the variable couple tuned
circuits.
Using a noise source instead of a spectrum analyser's tracking generator is not
ideal and the display is quite wobbly, but using a low display video bandwidth
and slow sweep rate (50Hz) helps.
Shows broad tuned circuit
Narrower & better skirt
Always wide & double hump
Almost ideal square top
See also my TECH buls on "RF Noise Bridge for LF, MF, & HF", "A Quality Crystal
Set" & "Spectrum Analyser mods 88-89".
Why don't U send an interesting bul?
73 de John G8MNY @ GB7CIP
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